Make better algorithm to find constraints

[o-nnerb]

When using the find method, EasyAnchor should lookup for constraints that are equal to the properties inside Anchor.

For example, I have set the anchor edges; width equal to height. To find the top constraint, I count use something like that anchor.top.find. In a scenario that there are a lot of constraints related to top, I could specify more attributes to find it like anchor.top.priority(750).constant(10)

[onmyway133]

@brennobemoura Hi, good point, would you like to make a PR? Another way is to just get a list of constraints from the view and filter

[o-nnerb]

I have already implemented, now I am testing

[o-nnerb]

See PR #5